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Published on: December 2, 2016
Identification of Proteins Associated with Multilamellar Bodies Produced by Dictyostelium discoideum
Alix M Denoncourt1,2,3, Valérie E Paquet1,2,3, Ahmadreza Sedighi1,2,3
1Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Quebec City, QC, Canada.
Abstract:
Dictyostelium discoideum amoebae produce and secrete multilamellar bodies (MLBs) when fed digestible bacteria. The aim of the present study was to elucidate the proteic content of MLBs. The lipid composition of MLBs is mainly amoebal in origin, suggesting that MLB formation is a protozoa-driven process that could play a significant role in amoebal physiology. We identified four major proteins on purified MLBs using mass spectrometry in order to better understand the molecular mechanisms governing MLB formation and, eventually, to elucidate the true function of MLBs. These proteins were SctA, PhoPQ, PonC and a protein containing a cytidine/deoxycytidylate deaminase (CDD) zinc-binding region. SctA is a component of pycnosomes, which are membranous materials that are continuously secreted by amoebae. The presence of SctA on MLBs was confirmed by immunofluorescence and Western blotting using a specific anti-SctA antibody. The CDD protein may be one of the proteins recognized by the H36 antibody, which was used as a MLB marker in a previous study. The function of the CDD protein is unknown. Immunofluorescence and flow cytometric analyses confirmed that the H36 antibody is a better marker of MLBs than the anti-SctA antibody. This study is an additional step to elucidate the potential role of MLBs and revealed that only a small set of proteins appeared to be present on MLBs.
Insights
Dictyostelium discoideum amoebae secrete multilamellar bodies (MLBs) containing specific proteins. This study identified four major proteins, aiding research into MLB function and protozoan physiology.
Area of Science:
- Cell Biology
- Biochemistry
- Microbiology
Background:
- Dictyostelium discoideum amoebae secrete multilamellar bodies (MLBs).
- MLB lipid composition suggests a protozoa-driven process significant for amoebal physiology.
- Understanding MLB protein content is crucial for elucidating their function.
Purpose of the Study:
- To identify the major proteins present in purified MLBs.
- To investigate the molecular mechanisms governing MLB formation.
- To contribute to understanding the physiological role of MLBs.
Main Methods:
- Mass spectrometry was used to identify proteins on purified MLBs.
- Immunofluorescence and Western blotting confirmed the presence of SctA.
- Immunofluorescence and flow cytometry evaluated MLB marker efficacy.
Main Results:
- Four major proteins were identified: SctA, PhoPQ, PonC, and a cytidine/deoxycytidylate deaminase (CDD) protein.
- SctA, a pycnosome component, was confirmed on MLBs.
- The H36 antibody was identified as a more effective MLB marker than anti-SctA.
Conclusions:
- MLB formation is a protozoa-driven process with potential physiological significance.
- A limited set of proteins is associated with MLBs.
- Further research is needed to determine the function of identified MLB proteins, including the CDD protein.
